Recently there has been an increasing number of surgeons using clips, in lieu of conventional suture ties, to occlude blood vessels and the like. In a typical surgical procedure, many veins, arteries and blood vessels must be tied off, prior to the severing thereof, in order to reach the surgical site. This is an often difficult and time-consuming procedure, since many vessels are located in areas where there is little room to work. It is important that the occlusion be positive to minimize bleeding and, due to the fact that once severed, the blood-carrying vessels tend to retract into surrounding tissue and are difficult to retrieve.
Prior art workers have devised numerous types of surgical ligating instruments designed to clip blood vessels. As used herein and in the claims, the term "blood vessel" or "blood vessels" should be considered in the broad sense to be inclusive of veins, arteries and the like to which ligator clips are normally applied. Prior art ligators can be divided into a number of general groups or categories.
First of all, reusable, permanent-type ligators have been developed which resemble a hemostat. Such ligators are provided with jaws configured to accept, remove and hold a single "V"-shaped or "U"-shaped clip from a fully separate dispensing cartridge. U.S. Pat. Nos. 3,631,707 and 4,187,712 teach exemplary hemostatic clip applicators falling within this general category. Such instruments are characterized by certain drawbacks. For example, they require constant maintenance and must be cleaned after each procedure and sterilized prior to each procedure. Such instruments are normally expensive and delicate. When such instruments are employed, normally two or more of them are used so that the nurse can be loading one while the surgeon is using another. The surgeon must refocus his eyes on the vessel at the ligation site each time he changes instruments. Furthermore, a clip can easily fall out of the instrument jaws, if the nurse or surgeon depresses the handle slightly and then relaxes prior to clipping. In many such instruments, it is often possible to form clips too tightly.
A second ligator category is comprised of ligating instruments which are permanent, reusable instruments resembling a pistol. Such instruments accept pre-sterile cartridges holding a multiplicity of clips. The clips are sequentially fed as the foremost clip is formed to occlude a vessel. This type of instrument eliminates some of the shortcomings of the single-clip devices described above, but creates some new problems of its own. For example, such ligators are extremely expensive and are complex, heavy and bulky. The instrument must be disassembled and cleaned after each use and sterilized prior to each use and, therefore, requires constant maintenance. Again, it may be possible to form clips too tightly. Exemplary ligators falling within this second category are taught in U.S. Pat. Nos. 2,968,041 and 4,246,903.
The third general category relates to ligators which are intended to be disposable, single-use, multi-feed instruments. As an example, disposable instruments have been made in accordance with the teachings of U.S. Pat. No. 4,299,224 and European published application No. 0,000,875. Such devices are also characterized by certain inherent problems. The clip load is limited and the clip feed mechanism is complex and somewhat awkward. In some instances, the handles of the ligator must be spread away from each other to locate a clip in the instrument jaws, after which the handles must then be squeezed toward each other to clamp the forwardmost clip. In other instances, the clip feed mechanism requires external manual manipulation between each clip-clamping step. As a result, such instruments frequently must be removed from certain limited surgical sites to accomplish the necessary clip advance manipulations, and in some instances it is possible to form the clips too loosely.
The instrument of the present invention overcomes all of the above noted shortcomings. The instrument is capable of pre-sterilization and constitutes a disposable, single-use instrument. It is provided with an extremely simple and reliable, substantially jam-proof, automatic clip feed system which requires no force or extra manipulation on the part of the surgeon. The instrument clamps a clip and presents the next clip for use in a single hand motion.
The ligator of the present invention is lightweight, provides maximum visibility of the clip during use and has an integral stop pin to prevent the tissue and clip from sliding rearwardly of the instrument jaw tips, enabling capture of the maximum amount of tissue. An adequate consistent and repeatable force is exerted on each clip during the clip clamping procedure so that the clamped clip provides maximum security without damage to the vessel caused by excessive pressure. The instant ligator has a large clip capacity and can be made in various sizes. It can be used with equal facility by both left-handed and right-handed surgeons. A clip can be partially formed without interrupting the feeding sequence of the next clip. Finally, an automatic lockout feature can be provided to make the instrument inoperable when empty.
The reliability of the clip feed system is of utmost importance. In instruments of the type utilizing a replaceable clip cartridge, when a jam occurs the cartridge and those clips remaining therein must be removed and replaced by a new cartridge. In those disposable instruments wherein the clip magazine constitutes a permanent non-removable part of the instrument, the entire instrument must be discarded and replaced when a jam occurs.
Prior art workers have devised many types of ligator clip feeding systems. For example, U.S. Pat. Nos. 4,166,466 and 4,316,468 teach ligator instruments utilizing clip magazines or cartridges containing stacks of clips. The lowermost clip of the stack is stripped therefrom by a pusher element during the clip-applying process. Magazines of this sort are limited with respect to their clip capacity and, since they extend laterally of the instrument, they tend to limit visibility and add to the bulk of the instrument.
U.S. Pat. No. 4,316,468 also teaches a magazine wherein the clips lie in the same plane and are located one behind the other. The clips are mechanically advanced in the magazine through the interaction of a series of leaf springs extending inwardly from the housing of the magazine and a series of leaf springs coupled to a clip loading blade. The clip loading blade is actuated by a lost motion link. The above mentioned European published application No. 875 teaches a magazine again having the clips lying one behind the other in the same plane. In this instance, the clips are mechanically advanced by means of the cooperating action of a feed blade and a ratchet blade. U.S. Pat. No. 4,296,751 teaches a clip advance system wherein the clips lie one behind the other in the same plane within a magazine and are constantly urged forwardly by a spring biased follower. Once the forwardmost clip of the row is located between the forming jaws of the instrument, the remainder of the clips of the row are retracted against the urging of the follower, to permit clearance for the instrument jaws to close and clamp the forwardmost clip. All of these exemplary systems are relatively complex, most of them requiring the interaction of numerous elements.
As indicated above, the ligator of the present invention provides an extremely simple clip feed system which is essentially jam-proof and extremely reliable. The clips, lying one behind the other in the same plane, are located in a clip tube and are constantly urged forwardly by a spring biased feeder shoe. The forwardmost clip of the row is transferred to a parallel pusher track by a simple ramp structure requiring no moving parts. The pusher, slidably mounted in the pusher track, locates the clips one-by-one in their proper position between the instrument jaws for clamping. Entrance of each clip from the clip tube into the pusher track is properly timed because it is controlled by the pusher itself, as will be described hereinafter.